1. Field of the Invention
The present invention relates to a graphics movement control system on a display screen which controls the intervals between drawing graphics according to the number of picture elements of the graphics when the graphics are moved on a display screen using a pointing device such as a mouse, etc. in an editor for editing a block diagram and a circuit diagram through a workstation, etc.
2. Description of the Related Art
When an editor processes a circuit diagram, etc. on a display screen, graphics are moved using a pointing device to any position on a display screen to perform an editing process easily and simply.
Converting the movement of a mouse to the movement of an object (graphics) on a display is generally referred to as "dragging".
In dragging graphics, if there is a time difference large enough to make an operator nervous between the movement of a mouse anti the actual movement on a display screen, then operability goes down and a malfunction may occur when another editing process is performed at any point until the movement on the display is completed.
Accordingly, in dragging graphics, graphics on a screen must be appropriately and visually moved in real time with the movement of a mouse.
With a conventional editor, specified graphics to be moved are moved unmodified when dragging graphics.
That is, as shown in FIG. 1 (PRIOR ART), when graphics 2 displayed on a display screen 1 are moved from position A1 to position A9 along a locus 3 of a mouse, then the graphics 2 at position A1 are first drawn at position A2 corresponding to the movement of the mouse, drawn at position A3, and then at position A3, A4, . . . Thus, the graphics are drawn sequentially at all sampling points of the mouse, and finally at position A9.
As described above, when the graphics 2 at position A1 shown in FIG. 1 are moved, the graphics to be moved are drawn sequentially at coordinate positions (A1, A2, . . . , A9) of the mouse at each sampling time, and are finally moved to the last position A9.
However, in the movement method described above, if complicated graphics composed using a number of dots and lines, that is, graphics composed of a number of picture elements, are to be moved, then the CPU, etc. incurs a large load, and the movement of the graphics cannot be traced on the screen in real time at the moving speed of the mouse. The reason is that it takes a long time to draw complicated graphics at each sampling position. Therefore, if the mouse is moved in a zigzag way, for example, the graphics must trace the zigzag movement. In this case, the graphics are further delayed in reaching the target position while following the movement of the mouse, resulting in the reduction of operability and a malfunction when another editing process is performed at any point until the movement is completed.
To prevent the above described problems, some editors redraw entire graphics object when graphics to be moved are selected, drag them as simplified graphics by drawing only the outline of the entire graphics. However, since some graphics are complicated in their outlines themselves, this method is not practical at all.